Inkjet printing systems can be either an on-axis or off-axis printer. In on-axis printing, printheads include inlet ports for receiving ink from one or more ink tanks. The printhead includes arrays of drop ejectors that receive the ink from the inlet ports and that are controlled to make marks of particular sizes, colors, or densities in particular locations on the recording medium in order to print the desired image. In some types of inkjet printing systems the array(s) of dot forming elements extends across the width of the page, and the image can be printed one line at a time, as the recording medium is moved relative to the printhead. Alternatively, in a carriage printing system (whether for desktop printers, large area plotters, etc.) the printhead or printheads are mounted on a carriage that is moved past the recording medium in a carriage scan direction as the dot forming elements are actuated to make a swath of dots. At the end of the swath, the carriage is stopped, printing is temporarily halted and the recording medium is advanced. Then another swath is printed, so that the image is formed swath by swath.
An inkjet drop ejector includes a nozzle and a drop forming mechanism (such as a resistive heater for thermal inkjet, or a piezoelectric device for piezoelectric inkjet) in order to generate pressure within an ink-filled chamber and eject ink from the nozzle. In page-width inkjet printers, as well as in carriage inkjet printers, the printhead and the recording medium are moved relative to one another as drops are ejected in order to form the image.
An ink supply can be permanently attached to a printhead, or an ink supply can be replace-ably connected to and disconnected from a printhead. Unlike printheads having permanently attached ink supplies, the printhead having replaceable ink tanks does not need to be discarded for a replaceable ink supply when the ink supply is depleted, so the running costs of the printer are lower for replaceable ink supplies. Ink tanks containing ink are installed into the printhead for supplying the ink needed for printing. Some types of ink tanks include an outlet port having a flange that contains a wick for permitting ink to pass to an inlet port of the printhead by capillary action. The inks tanks are manually mounted into a holding receptacle of the printhead by a pivoting, inwardly and downwardly manual force of the user. Some types of printhead include a flat gasket located on a floor of the holding receptacle, and a bottom of the flange of the outlet port of the ink tank is forced against the flat gasket when the ink tank is installed. Although such a sealing configuration works well in many applications, in some applications sealing against a flat gasket on the floor of the holding receptacle can require excessive installation force.
In an off-axis printing system, the printhead is substantially similar except that there is a primary ink supply and a secondary ink supply that are connected for supplying the ink for printing. The primary ink supply is rigidly mounted on the printer so that it remains stationary, and a secondary ink supply is mounted on the carriage. Ink is transferred from the primary ink supply to the secondary ink supply as needed. In this way, the amount of ink that is moved by the carriage is kept low (so that forces during carriage acceleration and deceleration can be acceptably low) and the user does not need to replace the ink very frequently.
To refill the secondary ink supply from the primary ink supply, flexible tubing is used, or alternatively the secondary ink supply can be moved near the primary ink supply on an as-needed basis and ink can be transferred to the secondary ink supply. Similar to the on-axis ink tanks, some types of secondary ink supplies include an outlet port having a flange that contains a wick that facilitates ink transfer to the printhead. A replaceable secondary ink supply for an off-axis printing system will be referred to herein as an ink tank, i.e. the same terminology used for the replaceable ink supply for an on-axis printing system.
In both on-axis and off-axis printing systems having replaceable ink supplies, the ink tanks (secondary ink supply for the off-axis) need to be installed. In both cases and particularly for the off-axis printing system, the ink tank can even be removed and replaced for maintenance.
U.S. Pat. No. 8,066,363 discloses an apparatus for securing an ink tank into a printhead. FIGS. 4a and 4b of U.S. Pat. No. 8,066,363 disclose three single gaskets 34, 45 and 47 and a retainer 30 among other things for securing the ink tank into the printhead. It is readily apparent that this apparatus is complex in design and is prone to failure due to the numerous interconnecting parts.
Consequently, a need exists for securing an ink tank to a printhead with low installation force by an apparatus that is simple in design and reliable over time. The present invention provides such an ink tank that meets this need.